1. Field of the Invention
The present invention relates to a substrate intended to configure an ink jet recording head (hereinafter also called an ink jet head) which performs operations, such as recording or printing characters, symbols, images, etc. by ejecting functional liquid, such as ink, against record bearing media, including paper, a plastic sheet, cloth, and an article; an ink jet head, which is configured by using the substrate; a recording unit which includes an ink reservoir for reserving ink to be fed to the ink jet head such as an ink jet pen; and an ink jet apparatus in which the ink jet head is installed.
Recording units according to the present invention, such as an ink jet pen, include those of a cartridge type into which an ink jet head and an ink reservoir are integrated and those of a combination type into which an ink jet head and an ink reservoir are combined so that the head and reservoir can be removed independently of each other. A recording unit, such as an ink jet pen, is adapted so that it can removably be attached to mounting means in an apparatus body, such as a carriage. Ink jet recording apparatuses according to the present invention include those which are provided integrally or separately as an output terminal for information processing equipment, such as word processors and computers; copying machines combined with an information reader etc., facsimile machines which send and receive information; and equipment which prints cloth.
2. Related Background Art
An ink jet recording apparatus can characteristically record a fine image fast by ejecting fine ink droplets from an ejection orifice at high speed. As disclosed in U.S. Pat. No. 4,723,129 and U.S. Pat. No. 4,740,796, ink jet recording apparatuses of such a type that ink is ejected using ink bubbling due to energy, especially thermal energy produced by an electric converter as energy producing means for producing energy used to eject ink have been the focus of attention because they can form a fine image and make a record at high speed and are suitable for reducing recording heads and recording apparatuses in size and providing color recording heads and recording apparatuses.
FIG. 1 shows a typical configuration of an ink jet head as described above.
FIG. 2 is a schematic sectional view of an ink jet recording head substrate 2000, taken along a line 2xe2x80x942 passing through an ink path in FIG. 1.
In FIG. 1, the ink jet recording head has a plurality of ejection orifices 1001, and an electrothermal converting element 1002 which produces thermal energy used to eject ink through the ejection orifices is provided on a substrate 1004 for each ink path 1003.
The electrothermal converting element 1002 mainly comprises a heating resistor 1005, electrode wiring 1006 which supplies power to a heating resistor, and insulating film 1007 which protects the resistor and wiring. The ink paths 1003 are formed by jointing together a plurality of top plates with which a path wall 1008 is integrated with, while aligning the plates with the electrothermal converting elements or the like on the substrate 1004. Each ink path 1003 communicates at its end opposite to the ejection nozzle 1001 with a common liquid chamber 1009, in which ink from an ink tank (not shown) is reserved. After fed to the common liquid chamber 1009, ink is directed therefrom into each ink path 1003 and held when it forms a meniscus near the ejection nozzles 1001. Thermal energy produced by selectively driving an electrothermal converting element 1002 is used to rapidly boil ink on a heating surface, so that ink is ejected by impulse due to boiling.
In FIG. 2, reference numerals 2001 and 2002 denote a silicon substrate and a heat storing layer (interlayer film) consisting of SiO2 film (heat oxidation film), SiN film, etc. Reference numeral 2003 denotes a heater; 2004, a heating resistor layer; 2005, wiring made of Al, Alxe2x80x94Si, Alxe2x80x94Cu, etc.; 2006, a least one protective layer consisting of SiO2 film, SiN film, etc.; 2010, a cavitation-resistant layer made of Ta film or the like, which protects the protective layer 2006 from chemical and physical impulse accompanying heat production by the heating resistor layer 2004; and 2008, a heating section of the heating resistor layer 2004.
The heating section 2008 generates heat due to pulse application caused by ink bubbling, and ink on the section rapidly boils when the section reaches about 300xc2x0 C. or more.
To bubble ink in such a way, the heating section is kept hot. In addition, to stabilize bubbling by inhibiting head quality variations and those in body driving, more energy than is required for ink to bubble need to be fed. As a result, the temperature of the heating section further increases. Under normal driving conditions, the temperature appears to reach 450xc2x0 C. to 550xc2x0 C.
Such a high temperature reached may cause a serious problem affecting the life of the head. The problem is that dye or pigment ink is exposed to high temperature, so that decomposition products produced by molecular chain cutting are deposited as xe2x80x9cscorchesxe2x80x9d on the heating section; that is, xe2x80x9ckogationxe2x80x9d occurs.
Owing to this xe2x80x9ckogationxe2x80x9d decomposition products are gradually deposited on the heating section, finally making it difficult to make ink bubble stably, affecting head life.
To prevent this phenomenon, various measures have been taken, including modifying ink components, such dyes, and adding to ink a component which prevents scorches.
However, a variety of demands are made on an image which an ink jet printer prints by ejecting ink. For example, these demands include increasing printed matter water resistance, preventing intercolor breed, and improving wear resistance. To meet these demands, ink components must be further modified. However, such modification may neutralize the effects of thus far taken measures for preventing scorches, thus reposing the problem of scorches. The present invention intends to prevent scorch deposits on the heating section and prolong recording head life even if such ink is used.
Japanese Patent Application Laid-Open No. 11-240156 discloses that water-repellent film is formed in an area corresponding to the heating section to prevent scorches from being easily deposited on the heating section and thereby inhibit bubbling efficiency reduction so that ink can stably bubble.
Japanese Patent Application Laid-Open No. 11-42798 discloses that a liquid which is low in surface tension and volatility than ink to be ejected is introduced into an ink path to break hydrophobic film on the internal surface of the ink path before ink to be ejected is introduced into the path, thereby helping ink wet the internal surface so that ink is easily introduced into the path. However, the publication does not disclose prevention of scorch deposits on the heating section. The method disclosed in the publication is not expected to provide hydrophilicity strong enough to satisfactorily prevent scorch deposits.
xe2x80x9cChemistry and Industryxe2x80x9d (No. 48, pp. 1256 to 1258, 1995) describes glass which is made hydophilic so that soil comes off spontaneously. xe2x80x9cChemistry and Industryxe2x80x9d [No. 49(6), pp. 764 to 767, 1996] also describes the effect of photo catalyst.
xe2x80x9cApplied Physicsxe2x80x9d [No. 64 (8), pp. 803 to 807, 1995] describes physical properties of material.
These descriptions relate to preventing soil deposits on a substrate surface or decomposing them by making the surface phydrophilic or forming a photo catalyst phydrophilic layer on the surface.
It is an object of the present invention to provide an ink jet recording head substrate, an ink jet recording head, an ink jet recording unit, and an ink jet recording apparatus which allow scorch deposits on the heating section to be prevented by exerting on the section effect of providing super-hydrophilicity, which is given by reinforcing the effect of providing hydrophilicity or effect of providing photo catalyst hydrophilicity.
It is another object of the present invention to provide an ink jet recording head substrate, an ink jet recording head, an ink jet recording unit, and an ink jet recording apparatus which allow heat to be efficiently conducted from the heating section to ink by giving the section super-hydrophilicity treatment.
An ink jet recording head substrate of the present invention with a plurality of heating resistors formed through an insulating layer on a substrate which produce thermal energy used to eject ink is characterized in that an area corresponding to a heating section in which heat produced by the heating resistors acts on ink is given super-hydrophilicity treatment and that the contact angle between the area and water is 5xc2x0 or less.
An ink jet recording head substrate of the present invention, which is adapted as described above, is characterized in that a layer of an amorphous alloy with the chemical composition expressed by the following chemical formula, a cavitation-resistant upper protective layer, is provided through at least one protective layer on the heating resistors and that the amorphous alloy layer is given the super-hydrophilicity treatment:
Taxcex1Fexcex2Nixcex3Crxcex4xe2x80x83xe2x80x83(1)
(where 10 atomic percentxe2x89xa6xcex1xe2x89xa630 atomic percent, xcex1+xcex2 less than 80 atomic percent, xcex1 less than xcex2, xcex4 greater than xcex3, and xcex1+xcex2+xcex4+xcex3=100 atomic percent).
An ink jet recording head of the present invention having an ejection orifice through which ink is ejected, an ink path which communicates with the ejection orifice and has a section exerting on the liquid thermal energy used to eject the liquid, and heating resistors which produce thermal energy is characterized in that an area corresponding to a heating section in which heat produced by the heating resistors acts on ink is given super-hydrophilicity treatment and that the contact angle between the area and water is 5xc2x0 or less.
An ink jet recording head of the present invention, which is adapted as described above, is characterized in that a layer of an amorphous alloy with the chemical composition by the following chemical formula, a cavitation-resistant upper protective layer, is provided through at least one protective layer on the heating resistors and that the amorphous alloy layer is given the super-hydrophilicity treatment:
Taxcex1Fexcex2Nixcex3Crxcex4xe2x80x83xe2x80x83(1)
(where 10 atomic percent xe2x89xa6xcex1xe2x89xa630 atomic percent, xcex1+xcex2 less than 80 atomic percent, xcex1 less than xcex2, xcex4 greater than xcex3, and xcex1+xcex2+xcex4+xcex3=100 atomic percent).
An ink jet recording unit of the present invention is characterized in that the unit has the ink jet recording head and an ink reservoir which stores ink to be fed to the ink jet recording head.
An ink jet recording apparatus of the present invention which has the ink jet recording head and recording signal feeding means for feeding a recording signal to drive the ink jet recording head is characterized in that ink is ejected from the ink jet recording head according to the recording signal to make records.
The present invention, designed as described above, prevents scorch deposits on the heating section, thus stabilizing ink ejection performance and allowing an ink jet head to be provided which lasts long and hardly depends on the components of ink. The present invention also provides an ink jet head with increased thermal conversion efficiency.
Especially, giving the heating section of an ink jet head super-hydrophilicity treatment causes the heating section to be satisfactorily wet with ink, so that thermal conductivity and bubbling efficiency increase.
The present invention allows ink jet head life to be prolonged. This is because the amorphous alloy layer, formed as a protective layer on the area, is not liable to corrosion due to various types of ink, so that the layer protects the heating resistors from chemical and physical impulse accompanying heat production by the resistors even if the area corresponding to the heating section, given super-hydrophilicity treatment, is partially washed out by cavitation impulse.